Energy drink outside - enjoy being unreal (9)
I believe the answer is:
dreamlike
'unreal' is the definition.
(similar in meaning)
'energy drink outside enjoy' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mcr).
'drink' becomes 'dram' (small alcoholic drink).
'outside' indicates putting letters inside (some letters go outside others).
'enjoy' becomes 'like' (like can mean to appreciate or enjoy something).
'e' going within 'dram' is 'dream'.
'dream'+'like'='DREAMLIKE'
'being' is the link.
(Other definitions for dreamlike that I've seen before include "Illusory" , "Imagined" .)